How to reduce PDF file size for email

How big can an email attachment be?

Most email services limit attachments to around 20 to 25 MB per message, for all the attachments together. Many company mail servers set lower limits, and some upload portals accept even less. Email also encodes attachments in a way that makes them roughly a third bigger on the way, so a file just under the limit can still bounce.

A safe target is under 10 MB for anything you send outside your organization, and smaller still if the person is likely to open it on a phone with a slow connection.

How to compress a PDF for email in PDFZyro

1. 1Open Compress on the Home page.
2. 2Add the PDF from your documents, or drop it in to upload it. You can add up to 20 documents and compress them together.
3. 3Choose the Compression level: Best quality (pictures up to 220 DPI), Balanced (150 DPI, recommended) or Smallest file (72 DPI, for screens).
4. 4Click Compress. Each document shows its size before and after, and how much smaller it got.
5. 5The smaller PDF is saved as a new version, and the full-quality original stays in its history. If a file can't be made smaller, nothing is saved.
6. 6Click Open, check that the pages still look right, then download the file and attach it to your email.

Which compression level to choose

Text and drawings made of lines stay sharp at every level, because compression works on the pictures. If Balanced isn't small enough, use Restore this version in the version history to go back to the original, then try Smallest file, so you're compressing the full-quality file rather than an already compressed one.

• Balanced: right for most documents. Pages read well on screen and print fine for everyday use.
• Best quality: for documents with photos or drawings that will be printed, or when you only need to save a little.
• Smallest file: for documents that will only be read on screen. Small text inside pictures and scans can become hard to read, so check every page.

Why some PDFs stay big

• It's mostly text already. Text takes very little space, so there's little left to save.
• It has files attached inside it. Remove hidden data removes attachments, along with metadata and leftovers of earlier saves.
• It has hundreds of pages. Even small pages add up, so send only the part that's needed.
• It's a colour scan at a high resolution. For text documents, scanning in greyscale or black and white at 300 DPI gives much smaller files that are still easy to read.

If it's still too big to email

• Split it by file size: Split can cut the document into parts that each stay under a size you choose. Send them in separate emails, and say how many to expect.
• Send only the pages that are needed: Extract pages copies them into a new, smaller PDF.
• Share a link instead of attaching the file. In PDFZyro, use Share to make a link, with an expiry date and a password if you like. The size of the file no longer matters.
• Use your email service's own option for large files: Gmail offers to send them as a Google Drive link, and Outlook as a OneDrive link.

Other ways to reduce PDF size

• Preview on a Mac: choose File, then Export, pick Reduce File Size from the Quartz Filter menu and save. It can shrink pictures a lot, so check that the result is still readable.
• Adobe Acrobat: the paid version has a Compress PDF tool. The free Acrobat Reader can't compress files.
• Microsoft Word on Windows: when you save a document as PDF, choose Minimum size (publishing online) to make the pictures smaller. This only works for documents you have in Word.
• Your scanner or scanning app: lower the resolution or choose greyscale before you scan, so the PDF starts small.